Measuring position is important for many human and servo control systems. Various methods exist to measure position. Many are rotary and some are directly linear. Linear designs are often costly or not entirely durable for high-frequency fluctuations in a small area. Inexpensive sensors such as potentiometers suffer from wear of the contact against the resistive medium. This is particularly problematic in situations where the transducer is continuously vibrating such as a simulator platform. Other systems, such as LVTs (linear velocity transformers), rely on a moving sensor and are not suited to measuring absolute position. Sill other systems are very accurate, such as the various precision systems used in CNC servo control, but are quite costly.